Packaging device for matrix-arrayed semiconductor light-emitting elements of high power and high directivity

ABSTRACT

A packaging device for matrix-arrayed semiconductor light-emitting elements of high power and high directivity comprises a metal base, an array chip and a plurality of metal wires. The metal base is of highly heat conductive copper or aluminum, and a first electrode area and at least one second electrode area which are electrically isolated are disposed on the metal base. The array chip is disposed on the first electrode area, on which multiple matrix-arranged semiconductor light-emitting elements and at least one wire bond pad adjacent to the light-emitting elements are disposed. The light-emitting element is a VCSEL element, an HCSEL element or an RCLED element. The metal wires are connected between the wire bond pad and the second electrode area to transmit power signals. Between the bottom surface and the first electrode area is disposed a conductive adhesive to bond and facilitate electrical connection between the two.

RELATED CASES

This is a continuation of co-pending Ser. No. 12/657,161, filed Jan. 14,2010, whose disclosures are incorporated by this reference as thoughfully set forth herein.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention is related to a packaging device formatrix-arrayed semiconductor light-emitting elements of high power andhigh directivity, and particularly to a packaging device which comprisesan array chip furnished with a plurality of semiconductor light-emittingelements arranged in an array, and is designed with specific wirebonding structure for providing good heat dissipation.

2. Description of the Prior Art

In recent years, optical communication technology has progressivelybecome the choice framework for network infrastructure, and is becomingthe main trend of data transmissions in the foreseeable future. Toincrease optical transmission efficiency, various semiconductor laserssuch as VCSELs (Vertical Cavity Surface Emitting Lasers), HCSELs(Horizontal Cavity Surface Emitting Lasers) and RCLEDs (Resonant CavityLight Emitting Diodes) have become the focal point of research anddevelopment efforts within the industry.

Conventional semiconductor lasers such as VCSELs are packaged by use ofa traditional TO-Can (Transistor-Outline-Can), for example, the TO-46type, wherein the semiconductor laser chip is adhered to the nickel-ironalloy substrate using colloidal silver (epoxy). However, a operationfrom upgrading to a watt-level.

Furthermore, the current number of laser elements disposed on a singlesemiconductor laser chip has reached up to 256 (16×16). In conventionalpackaging devices, the semiconductor laser chip is connected to thesingle electrode stem via wire bonding. However, in such conventionalpackaging devices, some metal wires are forced to traverse over thesemiconductor laser chip, blocking light emitted by some laser elements.In addition, connecting all the gold wires to a single electrode stemwill cause problems such as high resistance, high heat production andpoor heat dissipation, therefore requiring improvements.

SUMMARY OF INVENTION

The primary objective of the present invention is to provide a packagingdevice for matrix-arrayed semiconductor light-emitting elements of highpower and high directivity for resolving issues in the areas of wirebonding and heat dissipation.

In order to achieve the aforementioned objective, the present inventiondiscloses a packaging device for matrix-arrayed semiconductorlight-emitting elements of high power and high directivity. Thepackaging device comprises a metal base, an array chip and a pluralityof metal wires. The metal base is of highly heat conductive copper oraluminum, and a first electrode area and at least one second electrodearea which are electrically isolated are disposed on the metal base. Thearray chip is disposed on the first electrode area, on which multiplematrix-arranged semiconductor light-emitting elements and at least onewire bond pad adjacent to the light-emitting elements are disposed. Thelight-emitting element is a VCSEL element, an HCSEL element or an RCLEDelement. The metal wires are connected between the wire bond pad and thesecond electrode area to transmit power signals. Between the bottomsurface and the first electrode area is disposed a conductive adhesiveto bond and facilitate electrical connection between the two. Thepresent invention adopts a metal substrate comprised of copper, aluminumor gold, and uses a conductive adhesive with good heat conductivity,such as solder paste, to adhere an array chip. Compared to conventionaltechnology where nickel-iron alloy substrates and colloidal silveradhesion are employed, the present invention achieves superior heatconduction and dissipation effects. In addition, with the designstructure of the wire bond pad and electrode areas of the presentinvention, more metal wiring is allowed to transmit power signals,therefore providing advantages such as better heat dissipation, shuntedcurrents, reduced resistance, easy and flexible layout design, andreduced heat production, especially suitable for high power operatedsemiconductor light emitting elements packaging device.

In a preferred embodiment, the light-emitting elements are arranged as atetragon and the number of the wire bond pads is at least two anddistributed on different sides of the tetragon.

In a preferred embodiment, the number of the second electrode area isone and a width thereof is larger than a width of the array chip.

In a preferred embodiment, the number of the second electrode area is atleast two and corresponds in position to the wire bond pads.

In a preferred embodiment, at least one second electrode area among thesecond electrode areas is an L-shaped structure located at a corner ofthe array chip.

In a preferred embodiment, at least one third electrode area is furtherdisposed on the metal base.

In a preferred embodiment, the number of the at least one thirdelectrode area is at least two, and at least one thereof is an L-shapedstructure located at a corner of the array chip while the thirdelectrode areas and the first electrode area are electrically connectedvia a plurality of metal wires.

In a preferred embodiment, the packaging device further comprises acircuit board. The metal base is embedded on the circuit board, and thecircuit board is an LTCC substrate, an HTCC substrate or a plasticsubstrate.

In a preferred embodiment, the packaging device further comprises aplurality of stems extending from the circuit board. Wherein, the stemsare electrically connected to the first or second electrode area.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention as well as a preferred mode of use, further objectives,and advantages thereof will be best understood by referring to thefollowing detailed description of three preferred embodiments inconjunction with the accompanying drawings, wherein:

FIG. 1 is a top view of a first embodiment of the packaging device formatrix-arrayed semiconductor light emitting elements of high power andhigh directivity according to the present invention;

FIG. 2 is a top view of a second embodiment of the packaging device formatrix-arrayed semiconductor light emitting elements of high power andhigh directivity according to the present invention; and

FIG. 3 is a top view of a third embodiment of the packaging device formatrix-arrayed semiconductor light emitting elements of high power andhigh directivity according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a top view of a first embodiment of the packaging device formatrix-arrayed semiconductor light-emitting elements of high power andhigh directivity according to the present invention. In the firstembodiment, the packaging device 1 comprises a circuit board 2, a metalsubstrate 3, an array chip 4, and a plurality of metal wires 5.

The circuit board 2 is used to carry the metal substrate 3, and leads,stems, pins or terminals (not shown in FIG. 1) capable for electricalconnection to external printed circuit boards (not shown) are disposedbelow or laterally to the circuit board 2, wherein at least one hole 21is disposed on the circuit board 2. In this embodiment, the circuitboard 2 may preferably be an LTCC (Low Temperature Co-fired) substrate,an HTCC (High Temperature Co-fired Ceramic) substrate, or a plasticsubstrate.

The metal substrate 3 adhered to the circuit board 2 has a supportingsurface 31 for supporting elements such as the array chip 4 and metalwires 5. On the supporting surface 31 are disposed a first electrodearea 32 and at least one second electrode area 33, where as shown in thefirst embodiment in FIG. 1, the number of the first electrode 32 and thesecond electrode 33 is respectively one; furthermore, the width of thesecond electrode area 33 as shown in the top-down direction in FIG. 1 islarger than the width of the array chip 4. The first electrode area 32and the at least one second electrode area 33 are electrically isolatedby an insulating structure 34. In the first embodiment, the metalsubstrate 3 is comprised of copper, aluminum, gold, copper alloy,aluminum alloy, or gold alloy, and the first and second electrode areas32, 33 on the surface of metal substrate 3 may be selectively formed ofa layer of silver, copper, gold or the alloy thereof by means ofelectroplating, printing or deposition process, to improve theelectrical conductivity of the area and the adhesive force of wirebonding. The metal substrate 3 fabricated from copper, aluminum, gold orthe alloy thereof possesses better heat conducting and dissipatingcapabilities compared to conventional nickel-iron alloy substrates, andare therefore particular suitable for use in the high power operatedpackaging device 1 for semiconductor light-emitting elements. Theinsulating structure may be insulating paint or ceramic, or otherinsulating materials. In one embodiment, the metal substrate 3 extendedfrom top surface of the circuit board 2 to the bottom surface (backside) of the packaging device 1 for semiconductor light-emittingelements, not only for combination with the printed circuit board (PCB)configuring the packaging device 1, but also for enhanced heatdissipation effects.

The array chip 4 is disposed on the first electrode area 32 of the metalsubstrate 3. Multiple matrix-arranged semiconductors 41 and at least onewire bonding pad 42 are disposed on an active side of the array chip 4,wherein the light-emitting elements 41 may preferably be of VCSELs,HCSELs or RCLEDs. Furthermore, a conductive adhesive 43 is appliedbetween the bottom surface of the array chip 4 and the first electrodearea 32 for electrically connecting the two. In other words, the entiremetal substrate 3 becomes the grounded n-electrode due to contact of thefirst electrode area 32 and the bottom surface of the array chip 4,while only the second electrode 33 becomes the p-electrode. In the firstembodiment, the conductive adhesive 43 may preferably be solder paste.The present invention adopts highly heat conductive solder paste as theconductive adhesive 43 to bond the array chip 4 and the first electrodearea 32 of metal substrate 3, achieving better heat conducting anddissipating effects as compared to the conventional colloidal silveradhesion method, and is particularly suitable for use in the high poweroperated packaging device 1 for semiconductor light-emitting elements.In the present invention, the number of the light-emitting elements 41may be 256 (16×16) with peak power reaching 12-15 watts during pulseoperation. The light-emitting elements 41 are arranged as in the form ofa polygon, and the number of the wire bonding pads 42 is at least twoand on different sides of the polygon. In the embodiment shown in FIG.1, the light-emitting elements 41 are arranged into a tetragon while thewire bonding pads 42, in the number of two, are settled at twovertically opposite sides of the tetragon. However, in an alternativeembodiment, the wire bonding pads 42 may be on the adjacent sides of thetetragon.

The metal wires 5 are connected to the at least one wire bond pad 42 andthe at least one second electrode area 33 through a wire bondingprocess, wherein the metal wire 5 may preferably be gold. In thisembodiment, because the width of the second electrode 33 in the top-downdirection shown in FIG. 1 is larger than the width of the array chip 4,and the two wire bonding pads 42 are respectively on the opposing sidesof the light-emitting elements 41 of the array chip, the wires areextended obliquely outwards from the top and bottom sides of the arraychip 4, without traversing over the light-emitting elements 41 orsubsequently blocking the light-emitting elements 41 thereof, even ifthe number of the metal wires 5 is large. Moreover, due to a relativelylarger area of the second electrode area 33 adopted in the presentinvention and top and bottom side distribution of the wire bonding pads42 on the array chip 4, heat can be more effectively dissipated. Giventhe structure of the packaging device 1 for matrix-arrayed semiconductorlight-emitting elements of high power and high directivity allows formore metal wires 5 to transmit power signals, advantages such as shuntedcurrents, reduced resistance, easy and flexible layout, and reduced heatproduction, are achieved.

In the other preferred embodiments of the present invention describedhereinafter, since most elements are the same as or similar to those inthe aforementioned embodiment, like elements will be referred to by likenames and numbers, and an extra alphabet will be appended to theoriginal number for similar elements having the same name without anyparticular mention.

FIG. 2 is a top view of a second embodiment of the packaging device 1 afor matrix-arrayed semiconductor light-emitting elements of high powerand high directivity according to the present invention. In the secondembodiment, the packaging device 1 a also comprises a circuit board 2 a,a metal substrate 3 a, an array chip 4 a, and a plurality of metal wires5 a.

The metal substrate 3 a adhered to the circuit board 2 a has asupporting surface for bearing elements such as the array chip 4 a andmetal wires 5 a. Two first electrode areas 32 a (n-electrode) and twosecond electrode areas 33 a (p-electrode) comprised of copper, silver,gold or the alloy thereof, are disposed on the supporting surface bymeans of printing, electroplating, deposition or adhesion, to serve asthe metal pads for wire bonding. In the embodiment shown in FIG. 2, thetwo electrode areas 32 a are located on the left and bottom sides of thearray chip 4 a, applied with conductive adhesive 43 a towards the bottomsurface to the array chip 4 a, to enhance electrical and heat conductingeffects; the two second electrodes 33 a are located on the right and topsides of the array chip 4 a, isolated from the bottom surface of thearray chip 4 a by an insulating structure 34 a. Multiple matrix-arrangedsemiconductor light-emitting elements 41 a and two wire bond pads 42 aon the right and left sides of the light-emitting elements 41 a aredisposed on the active side of the array chip 4 a, forming anapproximate correspondence in terms of the locations of the two secondelectrode areas 33 a and the two wire bond pads 42 a. The metal wires 5a are connected between the two wire bond areas 42 a and the closersecond electrode area 33 a through wire bonding process. In thisembodiment, because the wire bond area 42 a left of the light-emittingelement 41 a and the second electrode area 33 a top of the array chip 4a are not adjacent, some of the metal wires 5 inevitably transverse oversome of the light-emitting elements 41 a. But since the light-emittingelements 41 a of the present invention are of the “high directivity”type such as of VCSELs, HCSELs or RCLEDs, the angle of emergence issmaller and thus less likely to be blocked by the metal wires 5 a.Therefore, the structure of the present invention is particular suitablefor use in the packaging device 1 a for matrix-arrayed semiconductorlight-emitting elements of high power and high directivity.

FIG. 3 is a top view of a third embodiment of the packaging device 1 bfor matrix-arrayed semiconductor light-emitting elements of high powerand high directivity according to the present invention. In the thirdembodiment, the packaging device 1 b also comprises a circuit board 2 b,a metal substrate 3 b, an array chip 4 b, and a plurality of metal wires5 b.

The metal substrate 3 b adhered to the circuit board 2 b has asupporting surface for bearing elements such as the array chip 4 b andmetal wires 5 b. In the embodiment shown in FIG. 3, a first electrodearea 32 b (n-electrode), three second electrodes 33 b (p-electrode), andthree third electrode areas 35 (n-electrode) are disposed on the metalsubstrate 3 b. The first electrode area 32 b is in contact with thebottom surface of the array chip 4 b and has larger area than the arraychip 4 b does, with conductive adhesive 43 b also applied towards thebottom surface of the array chip 4 b to enhance the electrical and heatconducting effects; the three second electrode areas 33 b are locatedrespectively on the top-left, top and top-right sides of the array chip4 b, isolated from the bottom surface of the array chip 4 b, the firstelectrode 32 b and the third electrode areas 35 by an insulatingstructure 34 b. The two second electrodes 33 b on the top-left andtop-right sides of the array chip 4 b are L-shaped and corresponding tothe corners of the array chip 4 b, for increasing the ease andflexibility of the wire bonding process and preventing the metal wires 5b from traversing over the array chip 4 b. The three third electrodes 35are located respectively on the bottom-left, bottom and bottom-rightsides of the array chip 4 b, all electrically connected to the firstelectrode area 32 b and each of the third electrode areas 35 throughwire bonding process. The two third electrodes 35 on the bottom-left andbottom-right sides of the array chip 4 b are L-shaped and correspondingto the corners of the array chip 4 b. In the embodiment in FIG. 3, thepackaging device 1 b further comprises a plurality of leads 6 extendingfrom the circuit board 2 b, wherein the leads 6 are electricallyconnected to the first or second electrode areas 32 b, 33 b,respectively. Through the use of this leads 6 structure, the packagingdevice 1 b for matrix-arrayed semiconductor light-emitting elements ofhigh power and high directivity of the present invention may be employedin surface mount devices (SMDs).

The present invention has been described with preferred embodimentsthereof, and it is understood that many changes and modifications to thedescribed embodiment can be carried out without departing from the scopeand the spirit of the invention that is intended to be limited only bythe appended claims.

What is claimed is:
 1. A packaging device for matrix-arrayedsemiconductor light-emitting elements of high power and highdirectivity, the packaging device comprising: a metal base having asupporting surface with a first electrode area and a second electrodearea disposed thereon, said first electrode area and said secondelectrode area being electrically isolated via an insulating structure;an array chip disposed on said first electrode area, wherein a pluralityof matrix-arranged semiconductor light-emitting elements and at leasttwo wire bond pads adjacent to said light-emitting elements are disposedon an active side of said array chip, wherein said light-emittingelements are arranged as a tetragon and said at least two wire bond padsare distributed on different sides of said tetragon; and a plurality ofmetal wires connected between said at least two wire bond pads and saidsecond electrode area; wherein, a pole of said second electrode area isopposite to another pole of the first electrode area; said at least twowire bond pads are connected by the metal wires to said second electrodearea and thus are of the same pole as said second electrode area;wherein the number of said second electrode area is one and a width ofsaid second electrode area is larger than a width of said array chip. 2.The packaging device of claim 1, wherein said second electrode area islocated near to a side of tetragon where no wire bond pad is beingdistributed.
 3. The packaging device of claim 2, wherein the number ofsaid at least two wire bond pads is two, said two wire bonding pads arerespectively on the opposing sides of the tetragon; and wherein, becausethe width of the second electrode is larger than the width of the arraychip and also because said second electrode area is located near to theside of tetragon where is no wire bond pad being distributed, thus themetal wires are extended obliquely outwards from the opposing sides ofthe tetragon, without traversing over the light-emitting elements. 4.The packaging device of claim 1, wherein said light-emitting element ischosen from one of the following: VCSEL element, an HCSEL element and anRCLED element; in addition, a material of said metal base is chosen fromone of the following: copper, aluminum, gold and an alloy of eithercopper, aluminum or gold; wherein a conductive adhesive is appliedbetween a bottom surface of said array chip and said first electrodearea for bonding, facilitating an electrical connection between saidbottom surface and said first electrode area; wherein said conductiveadhesive is solder paste; wherein the packaging device further comprisesa circuit board, said metal base being embedded on said circuit board,and said circuit board is an LTCC substrate, an HTCC substrate or aplastic substrate.
 5. A packaging device for matrix-arrayedsemiconductor light-emitting elements of high power and highdirectivity, the packaging device comprising: a metal base having asupporting surface with a first electrode area and a second electrodearea disposed thereon, said first electrode area and said secondelectrode area being electrically isolated via an insulating structure;an array chip disposed on said first electrode area, wherein a pluralityof matrix-arranged semiconductor light-emitting elements and at leasttwo wire bond pads adjacent to said light-emitting elements are disposedon an active side of said array chip, wherein said light-emittingelements are arranged as a tetragon and said at least two wire bond padsare distributed on different sides of said tetragon; a conductiveadhesive applied between a bottom surface of said array chip and saidfirst electrode area, facilitating an electrical connection between saidbottom surface and said first electrode area; and a plurality of metalwires connected between said at least two wire bond pads and said secondelectrode area; wherein said light-emitting elements are chosen from oneof the following: VCSEL elements, HCSEL elements and RCLED elements;wherein, a pole of said second electrode area is opposite to anotherpole of the first electrode area; said at least two wire bond pads areconnected by the metal wires to said second electrode area and thus areof the same pole as said second electrode area; wherein the number ofsaid second electrode area is one and a width of said second electrodearea is larger than a width of said array chip.
 6. The packaging deviceof claim 5, wherein said second electrode area is located near to a sideof tetragon where no wire bond pad is being distributed.
 7. Thepackaging device of claim 6, wherein the number of said at least twowire bond pads is two, said two wire bonding pads are respectively onthe opposing sides of the tetragon; and wherein, because the width ofthe second electrode is larger than the width of the array chip and alsobecause said second electrode area is located near to the side oftetragon where is no wire bond pad being distributed, thus the metalwires are extended obliquely outwards from the opposing sides of thetetragon, without traversing over the light-emitting elements.
 8. Thepackaging device of claim 5, wherein a material of said metal base ischosen from one of the following: copper, aluminum, gold and an alloy ofeither copper, aluminum or gold; wherein a conductive adhesive isapplied between said bottom surface of said array chip and said firstelectrode area for bonding, facilitating said electrical connectionbetween said bottom surface and said first electrode area; wherein saidconductive adhesive is solder paste; wherein the packaging devicefurther comprises a circuit board, said metal base being embedded onsaid circuit board, and said circuit board is an LTCC substrate, an HTCCsubstrate or a plastic substrate.